There's all sorts of latency problems caused by the congestion window size (and how it gets reset), because of how the algorithm works unless you're sending a c

There's all sorts of latency problems caused by the congestion window size (and how it gets reset), because of how the algorithm works unless you're sending a continuous stream of data (which allows the congestion window to grow) than the window gets reset to it's initial size which can mean waiting for an ack round-trip before you get the whole message. While it's not that big a deal if your users are local to you, if they're on a different continent each extra roundtrip can easily add 100ms. I used to do TCP/IP tuning for low latency trading applications (sometimes you need to use a third party data protocol so can't just use UDP), this sort of stuff used to bite us all the time. If latency is important it is worth sitting down with tcpdump and seeing how your website loads (i.e how many packets, how many acks, etc.) as often there are ways of tweaking connection setting (either via socket options or kernel settings) that can result in higher performance. (Try using tcp_slow_start_after_idle if you're using a recent linux kernel; this won't give you a bigger initial window, but it means once your window size has grown it won't get reset straight away if you have a gap between data sends)